Add mode configuration option

[martosaur]

💡 Motivation and Context

Should address #81 (see comment)

Changes:

1. Improve error for cases when user set enable: false in configuration but still tried to use default PostHog instance.
2. Introduce new configuration options mode :: :normal | :drop_events | :test. normal mode is, well, normal. test mode is basically current test_mode: true (and thus test_mode option is deprecated). drop_events simply drops all events instead of sending them to PostHog.

💚 How did you test it?

Unit tests

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran sampo add to generate a changeset file

[marandaneto]

@martosaur thanks for the PR but thats a breaking change and we cannot simply remove test_mode
You can simply start the SDK with enable: false when it's in testing mode
Another approach is to implement the before_send callback as the other SDKs do, so you can simply implement a callback that drops the event if it's in staging/dev mode

but still tried to use default PostHog instance.

we can fix this in this PR only and follow up with another PR for a different approach but lets not address both things here that also have a breaking change

[martosaur]

Hi @marandaneto , nice to meet you! Thanks for taking a look.

thats a breaking change and we cannot simply remove test_mode

That's a good call out! To be clar, the option is not removed, just merely deprecated. We still accept it and if passed, it will work as before. That should be backwards compatible change. I've pushed a test to better highlight this.

You can simply start the SDK with enable: false when it's in testing mode

enable: false works a little differently: it allows users to disable "managed" PostHog supervision tree to instead run it under their own application. This configuration option can't be used as a way to "turn off" posthog in dev. That's exactly the situation this comment is describing.

Another approach is to implement the before_send callback as the other SDKs do, so you can simply implement a callback that drops the event if it's in staging/dev mode

I'm confused, I don't see this callback anywhere?

[marandaneto]

@martosaur https://posthog.com/docs/libraries/python#disabling-requests-during-tests

SDKs should not throw if disabled is enabled or malconfigured, but instead log and be noop, this is gonna be fixed here eg #107
Another option is the before send eg https://posthog.com/docs/libraries/js/usage#amending-or-sampling-events
so you can do eg

config.before_send = { event
  if (DEV)
    return null
}

So I think this PR should not yet add another public API to address the very same issue.